UNTIL RECENTLY, President Obama dismissed the notion — “conventional wisdom,” as he called it — that a bipartisan budget deal would be more attainable if he made more personal effort to persuade Republicans in Congress to go along. In his view, the problem is mindless GOP obstruction, not insufficient presidential schmoozing.

He “can’t do a Jedi mind-meld with these folks and convince them to do what’s right,” he protested at a March 1 news conference. And there’s no “secret sauce” “to get [House] Speaker [John] Boehner or [Senate Republican leader] Mitch McConnell to say ‘You know what Mr. President, you’re right.’” That’s why he prefers to “speak to the American people about the consequences of the decisions that Congress is making or the lack of the decision-making by Congress.”

Well, maybe there’s no secret sauce. But the Jefferson Hotel serves a mean asparagus marmalade. And so Mr. Obama invited some Republican senators for dinner there, followed by lunch with House Budget Committee Chairman Paul Ryan (R-Wis.) and ranking member Chris Van Hollen (D-Md.). This was a welcome change of tone, and, possibly, strategy.

A grand bargain on debt reduction would need 60 votes to pass the Senate — all 53 Democrats plus at least seven others (two independents, Bernard Sanders of Vermont and Angus King of Maine, caucus with the Democrats). Among the GOP senators in Mr. Obama’s dinner party were several, such as Bob Corker of Tennessee and Tom Coburn of Oklahoma, who have expressed interest in a grand bargain before, as well as two — Mike Johanns of Nebraska and Saxby Chambliss of Georgia — who have already said they’re not running for reelection in 2014, and therefore have relative political freedom. If some personal attention, and, more important, visible public commitment from the president helps win their votes, well and good.

But the skeptics — including Mr. Obama himself — are right to this extent: No amount of warm personal interaction can overcome substantive disagreement, especially on tax increases and entitlement reform, both of which would have to be part of any deal worth having. Such a deal would not merely “stabilize” the national debt but would set it on a steady downward path.

Mr. Obama’s Republican dinner partners could and should respond favorably to his publicly announced proposal to raise $580 billion over the next decade by closing tax loopholes and limiting tax deductions to 28 percent of income for top earners. They can’t and won’t do that, however, without a bigger and more detailed commitment on entitlement reform than Mr. Obama has given publicly so far. Specifically, his offer of $400 billion in health-program savings over ten years strikes us as both too small and insufficiently fleshed out, though it’s a start.

As both sides involved in the Jefferson Hotel dinner recognize, the time between now and the next debt-ceiling renewal in August represents a last, best opportunity to cut a deal before the 2014 election campaign. If Mr. Obama and pragmatic Republicans can’t get something done in that time, their dinner will be remembered as just another in a long line of political gimmicks.